The present invention generally relates to improved means and methods for providing highly reliable, high capacity peripheral storage for use in a data processing system, and more particularly to a high capacity disk storage system comprised of multiple, independently operating disk drives cooperating with error correction circuitry in a manner so as to function as a high capacity disk drive having an unusually high fault tolerance level and a very high bandpass. The invention also contemplates the incorporation of a cache in a manner which significantly improves overall performance. In present day computer systems, the reliability of the peripheral storage system employed therewith is a critical item affecting overall system reliability, particularly where disk drives (today's favored peripheral storage devices) are used for peripheral storage. The primary reason is that the reliability of modern CPUs (computer processing units) has easily outstripped the reliability of the disk systems with which they are employed despite the intensive activity in recent years to improve the reliability of these disk systems.
The imbalance between the reliability of CPUs and disk systems has led to the development of data-base systems with audit trails which make it possible to reconstruct a data base after the failure and repair of the disk system.
Also, a so-called "mirrored disk" approach is typically used in which all data is written to two disk drive simultaneously, allowing easy recovery if one of them fails.
Known approaches (such as those mentioned above) for protecting the integrity of data in the event of disk failure are expensive either in direct equipment cost and/or in system performance. What is vitally needed, therefore, is a new approach for significantly increasing the reliability (fault tolerance) of a high capacity disk storage system which will not require the considerable expense and complexity of presently known approaches.